A thin film transistor-liquid crystal display (TFT-LCD), having advantages of a small size, low power consumption and radiation free, has been rapidly developed in recent years. The TFT-LCD includes: a liquid crystal display panel, a drive circuit and a backlight, in which the liquid crystal display panel is the most important portion in the TFT-LCD, which is formed by injecting a liquid crystal between two glass substrates, sealing surroundings between the two glass substrates by a sealant, and attaching two polarizers, of which their polarization directions are perpendicular to each other, onto the two glass substrates respectively. Among them, the upper glass substrate is a color filter, with three primary color filters (red, green and blue) constituting a pixel, and a transparent common electrode being plated on the color filter; and the lower glass substrate is a TFT array substrate, with a large number of thin film transistors arranging in matrix and some peripheral circuits being plated thereon.
As the glass itself is an isotropic medium, without influenced by any external forces, the glass itself does not generate a birefringence, however, in accordance with stress-optical law, in case the glass generates a stress change, due to a role of the stress, refractions of the glass towards different directions generate different changes respectively, so that the birefringence generates, resulting in light leakage (shown as FIG. 1). In the field of liquid crystal display, the light leakage resulted from the refraction changes along with glass deformation, is very unfavorable for display quality of the liquid crystal display screen.